The importance of pressure and vacuum testing of bulk transport equipment has always been recognized by responsible shippers and haulers, but with increasing concern for protection of the environment, such testing has reached the stage of critical importance for some industries.
Hazardous and biologically active chemicals and substances of all kinds must be carried over railroads and highways, and the public must be assured that the vehicles and containers are fit to carry these sometimes dangerous products. Just as commercial aircraft must be carefully inspected before each flight, good operating practices require that over-the-road tank trucks and trailers also be checked and verified free of leakage before being used to haul potentially toxic or hazardous materials.
Previous testing practices were often haphazard, and depended on the equipment and facilities available at the point of testing and filling. For example, some chemical haulers require each tanker to be individually tested before filling, and provide an electric vacuum pump to be attached to the tank vessel with appropriate fittings. A vacuum is drawn and held, and any significant change in the internal pressure over time signals the presence of a possible leak.
This kind of test is easy to do when the equipment is handy and there is an electric outlet to plug it in, but many locations are not so well situated. Also, this kind of testing apparatus can be heavy, awkward, and difficult to use in inclement weather. If an electric pump is required, then additional difficulties are presented in hazardous environments where no chance of sparking can be tolerated.
These and other obstacles with present testing equipment and procedures tend to discourage regular testing of hauling equipment, and every failure to test is a potential hazard to public safety should there be an undiscovered leak.
It is therefore an object of the present invention to provide a simple, inexpensive and easy-to-use testing apparatus with which an operator can quickly test his tank truck or car and related equipment with a minimum of effort.
It is a further object of the invention to provide such a tester which will readily test both positive and negative pressure environments (pressure and vacuum) with the same piece of equipment.
Another object of the invention is to provide a tester which is easily operated by hand, eliminating the requirement for a supply of compressed gas or a source of electric power, and which can be used in hazardous environments without the danger of sparking.